Electromagnetic drive for data indication

ABSTRACT

Electromagnetic drive for data indication includes a shell corelike magnet core, an excitation coil surrounding the magnet core, the magnet core having an inner sleeve-shaped core portion extending through the excitation coil, the inner core portion being formed with an air gap separating the inner core portion into two parts each formed with a magnetic pole, indicating means, and a plunger polarized in longitudinal direction thereof operatively connected to the indicating means, the plunger being freely displaceably disposed within the sleeve-shaped inner core portion and being displaceable from a neutral position thereof to a position wherein the indicating means are effective to provide an indication.

United States Patent [191 Y Heuer Nov. 27,1973

[ ELECTROMAGNETIC DRIVE FOR DATA INDICATOR [75] Inventor: Hans Heuer,l-leepen, Germany [73] Assignee: Anker-Werke AG, Bielefeld, Germany [22]Filed: July 6, 1971 [21] Appl. N0.: 159,782

[30] Foreign Application Priority Data July 6, 1970 Germany P 20 33378.2

[52] US. Cl 335/230, 197/1 R, 335/234 [51] Int. Cl. H0lf 7/08 [58] Fieldof Search 335/229, 230, 234; a 197/1 R [56] References Cited UNITEDSTATES PATENTS 3,202,886 8/1965 Kramer 335/234 2,749,453 6/1956 Cassellet al... 335/229 X 3,126,501

33/1964 Flora 335/254 X FOREIGN PATENTS 0R APPLICATIONS 1,136,41812/1968 Great Britain 335/234 Primary Examiner-George HarrisAttorney-Curt M. Avery et a1.

[5 7] ABSTRACT Electromagnetic'drive fordata indication includes a shellcore-like magnet core, an excitation coil surrounding the magnet core,the magnet core having an inner sleeve-shaped core portion extendingthrough the excitation coil, the inner core portion being formed with anair gap separating the inner coreportion into two parts eachformed witha magnetic pole, indicating means, and a plunger polarized inlongitudinal direction thereof operatively connected to the indicatingmeans, the plunger being freely displaceably disposed within thesleeve-shaped inner core portion and being displaceable from a neutralposition thereof to a position wherein the indicating means areeffective to provide an indication.

10 Claims, 6 Drawing Figures ELECTROMAGNETIC'DRIVE FOR DATA INDICATORThe invention relates to electromagnetic drive for data indicationwherein indicating means are transferred by a plunger from neutralposition thereof to indicating position thereof.

Heretofore known electromagnetically operated indicating systems such aswire, mosaic or typewheel printers or perforators orthelike, operate'ina manner wherein, for example, either the printing wire proper orprinting hammer of the amature leverof a magnet system, for example, aplunger-magnetsystem, is struck or the armature lever of the magnetsystem'proper is constructed as the indicating means (note GermanPublished Application. DAS 1,179,228 and- 1,262,053). 'A

pre-stressed restoring spring serves in most cases for returning thearmature lever to the neutral position thereof after an indication hastaken place (note German Published Application -1 253,940). Such drivesysterns have the disadvantage, however, that the force of the springacting in opposite direction to the direction of displacement of thearmature in the indicating direction, reduces the speed thereof, soth'at the speed of in- It is accordingly an object of the invention toprovide electromagnetic drive for data indicationwhich avoids theforegoing disadvantage of the heretofore known electromagnetic drives ofthis general construction and more specifically, to provide anelectromagnetic drive system of the plunger-magnet systemtype. for dataindication which is a major improvement over the heretofore'knowndevicesof this'general-typewithrespectto operational reliability and simplicityof construction,

and does not require the use of additionalmechanical components thataresubje'ct to wear. With the foregoing and other objects in view, thereis provided in accordance with the invention, electromagnetic drive fordata indication comprising a shell'core-like magnet core, an excitationcoil surrounding'themagnet core, the magnet core having aninnersleeve-shaped core portion extending through the'excitation coil, theinner core portion being formed with an air gap separating the innercore portion into two parts each formed with a magnetic pole, indicatingmeans, and a plunger polarized in longitudinal direction thereofoperatively connected to the indicating means, the plunger being freelydisplaceably disposedwithin the sleev'e shaped inner core portion andbeing displaceable'from a neutral position thereof to a position whereinthe indicating means are effective to provide an indication.

In accordance with another feature of the invention, the length of thesleeve-shaped core portion has a length which is a multipie of thelength-of the plunger,

and the air gap is located in the'middleof the coil so that the plunger,as viewed in direction of displacement by both of the magnetpoles-indicating position of the plunger.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin electromagnetic device for data indication, it is nevertheless notintended to be limited to the details shown, since various modificationsand structural changes may bemade therein without departing from thespirit of the invention and'within the scope and range of equivalents ofthe claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof 'will be bestunderstood from the following description of specific embodiments whenread in connection with theaccompanying drawing, in which: w

FIGS. 1 through 3 are diagrammatic longitudinal sectional views of theelectromagnetic drive for data indi-' cation according to the inventionshown in three different phases, namely in neutral or ofi-position, inindicating position, and after data indication, respectively;

' FIGS. 4 and 5 are diagrams of circuits for triggering theelectromagnetic drive; and I FIG. 6 is a longitudinal sectional view ofan actual embodiment of the electromagnetic drive of the invention.

Referring now to the drawing, and particularly to FIG. 1 thereof,'thereis shown diagrammatically the electromagnetic drive of the invention,which is in the form of a plunger=typemagnet system for data indication,and includes .a shell core-like magnetic core 1 cylindricallysurrounding an excitation coil 3 mounted on a coil form 2. The core part7 passing through the interior of the coil is of sleeve-likeconstruction and ,has an air gap 4 in the center of the coil so that twomagnetic poles 5 and 6 are formed, respectively, having effective poleends shaped conically on the exterior. thereof for the" purpose ofavoiding unnecessary leakage losses. Within the sleeve-like core part-7, a plunger 8 polarized in longitudinal direction is freelydisplaceably disposed, indicating means 9 in the form of a printing wirebeing secured thereto. The plunger 8, in the-phase illustrated in FIG.1, is in neutral position, as indicated by the fact that no current isshown traversing themagnet coil 3,

and is completely inserted into the sleeve-like magnet pole 6 where itis retained permanent-magnetically. The-length of the core part 7 is amultiple of the length of the plungerS. A stop 10 of non-magneticmaterial, preferably of plastic material, serves as a positionsecuringdevice for the plunger 8 and is provided with a ventilation or air hole11 to avoid air damping. An indication carrier, representeddiagrammatically by the line 12, against which the printing wire 9,connected to thereof, is surrounded entirely or partly" by one of thethe plunger 8, directly strikes.

In the indicating-position phase of the electromagnetic drive of theinvention shown in FIG. 2, the polarized plunger 8 is located in the airgap 4 between the magnet poles 5 and 6 where it is equally surrounded byboth of the magnet poles 5 and 6 so that a'closed magnetic circuit isformed, the magnetic field produced by theexcitation coil 3 beingrepresented. by the dotted line, as shown. Totransfer the plunger' 8from the off:

position thereof of FIG. 1 into the indicating position thereof of FIG.2, voltage is applied to the excitation coil 3 so that the magneticfield that is formed in opposite in direction to that of the outermagnetic field of the plunger 8. By reversing the polarity of thecurrent direction in' the excitation coil 3, the direction of themagnetic field is reversed (note FIG. 3), so that the plunger 8, becauseit is polarized, is driven out of the air gap 4 back into theoff-position thereof wherein, as mentioned hereinbefore, it is retainedpermanentmagnetically after the excitation voltage has been switchedoff. The polarity reversal of the current direction preferably occurs atthe instant the printing wire indicating means 9 strikes the indicationcarrier 12. The displacement of the plunger 8 back into the originallocation thereof .shown in FIG. l-is reinforced in this way by therebound thereof from'the indication carrier 12.

The circuits shown in FIGS. 4 and 5 serve to control the foregoingoperation of the electromagnetic drive for data indication constructedin accordance with the invention. FIG. 4 shows the aforementionedexcitation coil 3 having one terminal thereof connected through acapacitance l3 and a selector switch 15 to a reference voltage source V,and the other terminal thereof through a series resistance 16 to apositive voltage +U. Furthermore, a discharge resistor 14 is providedwhich, upon reversing the switch 15, is connected in parallel with theseries connection formed by the excitation coil 3 and the capacitance13. The position of the selector switch 15 shown in FIG. 4 correspondsto the neutral position of the plunger 8 in the phase illustrated inFIG. 1. The capacitance 13 is charged, and no current flows through .theexcitation coil 3. The charging time depends upon the dimensioning orrating of the series resistance 16 and the excitation coil 3. For anindicating operation, the position of the selector switch 15 is variedso that the capacitance l3 discharges through the discharge resistance.14. The discharge current consequently flowing through the excitationcoil 3 produces a' magnetic field (note FIG. 2) which transfers theplunger 8 rapidly into the indicating position thereof. Resetting of theselector switch 15 to the original position thereof shown in FIG. 4results in renewed charging of the capacitance 13 with opposing currentdirection (note FIG. 3) so that the plunger 8 rapidly returns to theneutral position thereof shown in FIG. 1.

The circuit diagrammatically shown in FIG. corresponds in constructionto that shown in FIG. 4, with the difference, however, that the selectorswitch of FIG. 4 is replaced by two transistors 15a and 15b in FIG. 5.The pulse diagrams shown in FIG. 5 at the bases of the transistors 15aand 15b indicatethat in neutral position of the plunger 8 the transistor15a is conductive and the transistor 15b is blocked. Further discussionregarding the triggering or control of the transistor 15a and 15b willnot be made herein since it can be carried out in any conventionalmanner known to the man of ordinary skill in the art. In theembodimentof thecircuit' shown in F IG. 5, npn transistors are used,.however the circuit can be suitably adapted .for pnp transistors.

In FIG. 6, there is shown in longitudinal section, the actual structureof the electromagnetic drive.20 of the invention which has been showndiagrammatically in FIGS. 1 to 3. An excitation coil 21 is mounted on acylindrical coil form 22 which is carried by two flanges 23 and 24having, respectively, a sleeve-like extension 26,

25. The sleeve-like extensions 25 and 26 are inserted.

into the coil form 22 so that two opposing magnet poles 25a and 26a areformed, having pole ends of conical construction at the-outside thereof.A plunger 27, as aforedescribed with respect to FIGS. 1 to 3, ispolarized in longitudinal direction thereof and is of tubularconstruction. Guide flanges 28 and 29 are constructed with the endfacesof the-polarized plunger 27. They are made of non-magnetic materialand are formed with recesses 30 and 31 extending in the direction ofdisplacement of the plunger 27, for reducing the mass of the flanges 28and 29. The plunger 27 is freely displaceably disposed within thesleeve-like extensions 25 and 26 of the respective flanges '23 and24."Aslocation- 'securing device for the plunger '27 in theneutr'al'p'ositionthereof, a stop 32 formed with an air hole 33 is the invention in anon-illustrated carrier part, the

flange 23 facing in direction toward the location at which thenon-illustrated indication carrier would otherwise be, is provided witha connecting piece 36 formed with a thread 37. The outer magnetic returnleg of the magnet system is formed by a sleeve 39 that is slid over theexcitation coil 21 and is connected, for example, to both flanges 23 and24 respectively having the extensions 26 and 25, and provides a shellcore-like shape to the magnet core constructed of these components. Asdescribed hereinbefore, the sleeve 39. forming the outer leg of themagnetic circuit is located between the two flanges 23 and 24. A closemagnetic force lock can be produced by rolling and flanging the outermagneticreturn-,leg, so-that the sleeve 39 surrounds both flanges 23 and24.

In the illustrated embodiment of FIG. 6, the indicat ing means 38 isconstructed as a.printing wire, so that when a number of theseelectromagnetic drives 20 are combined into one unit, there results,for, example, a complete wire printing mechanism.

The structure of the indicating means 38 can obviously also be needle orhammer-shaped so that the aforedescribed embodiment of theelectromagnetic drive 20 is capable of being used as well forconventional needle printers or fast printers.

The advantages attained by the invention are especially that,-'due tothe very small mass being displaced, a high indicating speed isattained,and this indicating speed, because no increasing counter-force,such as for a spring, need be overcome, is very rapidly achieved.

Iclaim;

l. Electromagnetic drive for data indication comprising a shellcore-like magnetic core, an excitation coil surrounding said magnetcore, said magnet core having an inner sleeve-shaped core portionextending through said excitation coil, said inner core portion beingformed with an air gap separating said inner core portion into two partseach formed with a magnetic pole, indicating means, and a plungerpolarized in longitudinal direction thereof operatively connected tosaid indicatingmeans, said plungerbein'g freely displaceably disposedwithin said sleeve-shaped inner core portion and being displaceable froma neutral position thereof to a position wherein said indicating meansare effective to provide an indication.

2. Electromagnetic drive according to claim 1 wherein saidsleeve-shapedinner core portion has a leng-ththat is a multiple of thelength of said plunger, and said air gap is located in the center ofsaid coil. v

3. Electromagnetic drive according to claim 1 wherein said plunger, inneutral position thereof, is at least partly surrounded by one of saidmagnetic poles and, in said position thereof wherein said indicatingmeans are effective, is surrounded by both of said magnetic poles. I

4. Electromagnetic drive according to claim 3 wherein the magnetic polesof said magnet core are polarizable, in one indicating operation, sothat transfer of said plunger into both the positions thereof whereinsaid indicating means are effective, as well as into said neutralposition thereof, is accelerated.

5. Electromagnetic drive according to claim 4 includ ing means forproducing an outer magnetic field in given direction in said plunger andmeans for producing with said excitation coil a magnetic field indirection opposite to said given direction for transferring said'plungerfrom neutral position thereof to the position thereof wherein saidindicating means are effec- 6. Electromagnetic drive according to claim1 including adjustable stop means disposed in one of said sleeve-shapedcore positions for adjusting the neutral position of said plunger.

7. Electromagnetic drive according to claim 6 wherein said stop means isformed with an air hole.

8. Electromagnetic drive according to claim 6 wherein said stop means isformed of a sound-proofing, elastic plastic material.

9. Electromagnetic drive according to claim 1 wherein said plungercomprises a member of tubular construction and a pair of guide flangeslocated respectively at opposite ends of said member, one of said guideflanges facing in direction toward said position of said plunger whereinsaid indicating means are effective, said one guide flange beingconnected to said indicating means.

10. Electromagnetic drive according to claim 9 wherein said indicatingmeans has a wire-shaped construction.

1. Electromagnetic drive for data indication comprising a shellcore-like magnetic core, an excitation coil surrounding said magnetcore, said magnet core having an inner sleeve-shaped core portionextending through said excitation coil, said inner core portion beingformed with an air gap separating said inner core portion into two partseach formed with a magnetic pole, indicating means, and a plungerpolarized in longitudinal direction thereof operatively connected tosaid indicating means, said plunger being freely displaceably disposedwithin said sleeve-shaped inner core portion and being displaceable froma neutral position thereof to a position wherein said indicating meansare effective to provide an indication.
 2. Electromagnetic driveaccording to claim 1 wherein said sleeve-shaped inner core portion has alength that is a multiple of the length of said plunger, and said airgap is located in the center of said coil.
 3. Electromagnetic driveaccording to claim 1 wherein said plunger, in neutral position thereof,is at least partly surrounded by one of said magnetic poles and, in saidposition thereof wherein said indicating means are effective, issurrounded by both of said magnetic poles.
 4. Electromagnetic dRiveaccording to claim 3 wherein the magnetic poles of said magnet core arepolarizable, in one indicating operation, so that transfer of saidplunger into both the positions thereof wherein said indicating meansare effective, as well as into said neutral position thereof, isaccelerated.
 5. Electromagnetic drive according to claim 4 includingmeans for producing an outer magnetic field in given direction in saidplunger and means for producing with said excitation coil a magneticfield in direction opposite to said given direction for transferringsaid plunger from neutral position thereof to the position thereofwherein said indicating means are effective, and for producing amagnetic field in the same direction as said given direction fortransferring said plunger from the position thereof wherein saidindicating means effective to said neutral position thereof. 6.Electromagnetic drive according to claim 1 including adjustable stopmeans disposed in one of said sleeve-shaped core positions for adjustingthe neutral position of said plunger.
 7. Electromagnetic drive accordingto claim 6 wherein said stop means is formed with an air hole. 8.Electromagnetic drive according to claim 6 wherein said stop means isformed of a sound-proofing, elastic plastic material.
 9. Electromagneticdrive according to claim 1 wherein said plunger comprises a member oftubular construction and a pair of guide flanges located respectively atopposite ends of said member, one of said guide flanges facing indirection toward said position of said plunger wherein said indicatingmeans are effective, said one guide flange being connected to saidindicating means.
 10. Electromagnetic drive according to claim 9 whereinsaid indicating means has a wire-shaped construction.